Hand powered instruments useful for biting tissues, known as rongeurs are common in the field of surgery. While there are many variations designed for use by one hand, the most common by far, would be the Pituitary, Kerrison, and Leksell types.
Prior hand operated rongeurs of the pituitary type have been characterized by a scissors like construction, with thumb and index finger grip holes, or of the Kerrison type using the thenar-palm line and four fingered handle. In these and other available designs, the forefinger is used to actuate the instrument from a position offset from the actuating operating mechanism so that the force required to close and open the instrument also translates in part into an upward displacement of the operating shaft and tip of the instrument. Not infrequently the surgeon finds it necessary to post the tip of the instrument into healthy tissue in order to limit the movement of the tip before biting or cutting the tissue to be removed. This injures healthy tissue. Also, due to the orientation of the hand and fingers, the location of the tip of the instrument is difficult to be mentally perceived, much less controlled, by the surgeon.
There is, therefore, a need for an improved handle for surgical instruments.
The present invention consists of a rongeur having a main body portion which is the longitudinal proximal extension of the working shaft of the instrument. The most rearward portion of the body portion extends for approximately one inch over the dorsum of the hand, specifically in the notch formed by the junction of the thumb and index finger to the hand. Just distal to the proximate end of the body member, is the rear arcuate handle, the arc facing the rear end of the instrument. This rear handle is affixed to the body portion at essentially 90 degrees to the long axis of the body portion and will anatomically conform to the shape of the thenar eminence (the prominence of the muscles of the thumb) when the hand is in the xe2x80x9cBang Bangxe2x80x9d, xe2x80x9cFake Gunxe2x80x9d or index finger pointing with the thumb extended position. In fact, the hand in grasping the instrument will, by means of said fixed proximal handle contour, be coaxed into assuming the desired position.
The lower portion of the rear handle continues, where it may either become convex or continue in line with the thenar portion, in which event said member would follow the shape of the thenar proximal, but would be more ulnar (towards the little finger side of the hand) such that in either case the ulnar border of the hand would be driven more proximal beneath the thenar""s and with a tendency for the wrist, if unresisted, to assume a more extended (cocked-up) position. Spaced from the rear handle member of the instrument is a front downwardly disposed, pivotable arcuate handle member, of a length sufficient to accommodate the long, ring and little fingers of the hand. The lower portion of the front handle may be curved to facilitate finger placement and provide for a cradling of the lowest finger, thereby providing for a better feel and more control. A spring mechanism associated with the front handle, is utilized to urge the front handle to its original forward position. In alternative embodiments, the front handle may be fixed and provided with a trigger housing and mechanism for activating the rongeur. For example, if the rongeur is electrically powered, the trigger within the housing would activate the rongeur.
The instrument of the present invention is grasped quite differently from all other prior surgical instruments in that the index finger is separated from the remaining three fingers and is left extended along the main shaft of the instrument, pointing, while the three remaining fingers are wrapped around the unusually short front handle or trigger. The thumb is fully extended and may come to rest in more distal position, relative to its natural resting position and to the other fingers of the hand, as the shape of the rear handle urges the thumb portion of the hand forward and the wrist into a more extended (cocked-up) position. The part of the body portion coming to lie between the thumb and index fingers, which are relatively opposed, is called the xe2x80x9cpinch padxe2x80x9d area of the body portion of the instrument.
The following advantages of the present invention are a product of the handle design and the induced finger, hand, and wrist positions:
1. Ambidextrous.
2. Anatomic to the working position profile of the inside of the partially closed hand.
3. Anatomic to and thus induces the optimal functional finger, hand and wrist positions.
4. Recruits the xe2x80x9cAutomatic Hand Effectxe2x80x9d to optimize the instrument function. If no attempt is made to inhibit it, it can be observed that taking the fingers from the fully extended position with the hand straight out to the semi-closed finger grasping position, causes the wrist to go into the xe2x80x9ccocked-upxe2x80x9d position automatically. This effect is deliberately elicited by the handle design and is beneficial in at least two ways. Firstly, it allows for the proper alignment, discussed below, and secondly it improves the finger flexion function, as described below in Item 6.
5. While the handle design deliberately elicits the described wrist extension, this in fact results in the absolute longitudinal alignment of the surgical instrument through the hand and wrist with the forearm.
6. Finger flexion. The means of operating these instruments is facilitated by wrist extension. This is easily proven by assuming the opposite position and attempting to make a fist with the wrist fully flexed.
7. Elimination of the operating shaft/hand vertical displacement, increasing control.
8. Maximalization of hand contact is achieved for added control. The thumb and index fingers contact the body portion throughout their entire length. The palm engages the handle across its entire breadth, with the thenar engaging and almost encircling the rear handle portion. The three remaining fingers literally wrap around the front handle portion.
9. Minimalization of skin contact pressures.
10. Fits all size hands, because the lower three fingers wrap the pivotal front handle or trigger, and since it does not matter whether it is more proximally or distally, the handle will function well, and feel good to hands of all sizes.
11. Increased mechanism capacitance of springs and the like in the body portion.
12. The surgeon""s hand is not exposed to any sharp or moving parts.
13. Enhanced instrument stability. The opposition of the thumb and index fingers on either side of the xe2x80x9cpinch padxe2x80x9d stabilizes the instrument against side to side movement, while the instrument is also stabilized against any up and down movement by both the rear and front handles, which have both upper and lower contoured stops.
14. Ergonomic. The handle is biomechanically engineered to facilitate the human hand function in its operation.
15. Proprioceptive. Proprioception or kinesthetic sense is the ability to correctly spacially locate a bodily part without the use of vision. This allows one to easily place a finger in the ear or on the tip of the nose, even with the eyes closed. The index finger first, and the tactile pulp of the thumb secondly, are the most richly invested with this kinesthetic capacity. Prior rongeurs have failed to take advantage of this, and have allowed both the index finger and thumb to face away from the intended target, or to be curled up in and upon themselves. The present design aligns the index finger and thumb along the longitudinal axis of the instrument such that they always point exactly at the target, and thereby facilitate the accurate placement of the instrument by the operator, without the need to visually monitor that action. This is extremely important as it allows the surgeon to remain focused at the surgical site even as the instrument is passed into and away from that site, and without the need for the surgeon to perform continuing and repetitive disruptive reorientations.
16. The absence of reactive tip excursion. Since the typical rongeur provides for only two points of hand fixation to the handle, when an attempt is made to operate the instrument by imparting of force at the handle, there is an excursion of the tip, according to Newton""s 3rd law of action and equal reaction, such that the tip is moved from the intended targeted tissue. With the present invention, stabilization of the instrument distal to the application of the trigger force, at the xe2x80x9cpinch padxe2x80x9d, allows for the requisite reactionary counter force required to neutralize the proximal force, thereby leaving the tip free of any undesirable excursion during the instrument""s operation.
17. The design is compact and requires reduced operating space because of the absence of any vertical displacement of the grasped area from the instrument shaft axis and by aligning the instrument axis and containing the entire handle within the hand. As a direct result, smaller incisions and less wound retraction is required for the operation of instruments with handles so designed.
18. Ultra-low profile.
19. Enhanced sight visualization as the view of the tip is unobstructed by any protrusions.
20. Line of sight targeting. The instrument design facilitates the accurate aiming of the instrument, much like sighting a rifle. The extended index finger and aligned instrument shaft are like the rifle barrel, while the instrument tip is the front bead, and the anatomical xe2x80x9cVxe2x80x9d of the thumb and index finger, bisected by the proximate handle extension, is the rear targeting site.
21. Universality. This handle""s design can be utilized for a large variety of previously disparate rongeur types, thereby facilitating surgery, in that each instrument feels and operates in the identical fashion.
22. Increased comfort.
23. Increased maneuverability.
24. A stronger and more rigid instrument. The overall length of the instrument and displacement of the handle from the axis of the instrument are minimized by aligning the instrument within the hand and containing the handle therein. Reduction of the instrument length and the displacement of the points of application of force to the extended lever arm results in a more rigid and stronger construct.
25. More durable.
It is therefore an object of the present invention to provide an improved handle for a medical instrument that is ergonomic;
It is another object of the present invention to provide an improved handle for a medical instrument that is easier to use;
It is another object of the present invention to provide an improved handle for a medical instrument that automatically correctly positions the hand of the user on the instrument;
It is another object of the present invention to provide an improved handle for a medical instrument that is more comfortable and causes less fatigue during use;
It is another object of the present invention to provide an improved handle for a medical instrument that is more durable;
It is another object of the present invention to provide an improved handle for a medical instrument provides for improved proprioception of the instrument tip;
It is still another object of the present invention to provide an improved handle for a medical instrument that is more stable.
These and other objects of the present invention will be apparent from a review of the following specification and the accompanying drawings.